Ball-Bearing Ratchet Screwdriver

This 3d-printable ratchet screwdriver is very strong, as it uses
metal 4.5mm airgun BB's instead of plastic catches. The mechanism turns
freely forward, locks solid backwards,
see the video.
It has a 1/4" hex in the axle for screwdriver bits. You could also use
it as an overrunning clutch.